Override Koa version

[jibrang]

What approach did you choose and why?

We are implementing an override to use version 2.16.2 of the koa npm package to address the following security vulnerability: https://github.com/github/browser-support/security/dependabot/38.

This approach is recommended because koa is a transitive dependency, and some dependencies continue to use the vulnerable version. Overriding ensures our project uses a secure version until upstream dependencies are updated.

Verified that we are using the correct koa version after the update:

 npm ls koa
@github/browser-support@1.2.2 /workspaces/browser-support
└─┬ @web/dev-server-esbuild@1.0.4
  └─┬ @web/dev-server-core@0.7.5
    └── koa@2.16.2 overridden

[Copilot]

Pull Request Overview

This PR adds a security fix by overriding the koa npm package version to 2.16.2 to address a security vulnerability in transitive dependencies that continue to use vulnerable versions of koa.

• Adds npm overrides configuration to force use of secure koa version
• Addresses security vulnerability https://github.com/github/browser-support/security/dependabot/38
• Ensures all transitive dependencies use the patched version until upstream updates